In the field of heavy duty industrial gas turbine engines it is important to ensure that the component exposed to the hot gas flow, in particular downstream of the combustion chamber, is at a temperature level which does not harm the corresponding components. Therefore rotating or stationary gas turbine airfoils, typically made of or at least based on metal, have to be cooled internally. To this end they comprise cooling channels provided in the air foils which are supplied with cooling air typically discharged from the compressor end exit. On the one hand cooling is effected by circulation of this cooling air in these internals channels, on the other hand by bores provided in the wall structure of the air foil leading to a blowing-out of the cooling medium and a film cooling at the location of the exits of the cooling hole and downstream thereof.
In particular the air foil trailing edge is required to be maintained at a low metal temperature.